The strong inward rectifier potassium channels are involved in action potential repolarization, modulation of cell excitability, and determination of cell resting potential in the brain and other excitable cells. Indeed, mutations in these channels are associated with defects in cell excitability, periodic paralysis, cardiac arrhythmias, and developmental abnormalities. Recently, it has been demonstrated that proteins that are associated with ion channels may modulate the functional properties of the channels, and such interactions may have profound implications in normal physiology and disease. Defects in channel-interacting proteins could lead to problems in channel expression, membrane targeting, association of channels with signaling complexes, and channel electrical activity. This proposal aims to identify and characterize the proteins that interact with inward rectifier potassium channels. Recently, we have identified such an interaction between inward rectifier channels and the scaffolding protein SAP97 in the brain. The goal of this project is to identify the complex of proteins that associate with inward rectifier potassium channels and to analyze the functional ability of these proteins to cluster, localize and regulate the activity of the channels.